A butane micro-torch (similar to the ones used by chefs for creme brulees) is used to seal the capillaries. The flame needs to be small - about 5mm across - so that you do not heat your sample or burn your fingers when sealing the capillaries. These can be bought from RS components or can be obtained from Amazon from the kitchen department. You may also find them in hardware shops and places that sell kitchenware. These torches are refillable and use the same butane that is used in cigarette lighters.
Tweezers/blunt ended forceps are used when sealing the capillaries. You can use any type of tweezers so long as you can easily grip the glass capillaries with them; a pair similar to those shown below would be the easiest to use.